OpenAI Releases the o3 Reasoning Model Preview

OpenAI previewed o3 in December 2024 as a successor to the o1 reasoning family. The announcement emphasized stronger performance on mathematics, coding, science, and difficult benchmark tasks.

The model continued the idea of allocating more inference-time computation to hard problems. This approach is different from scaling only by training a bigger model once: the system can spend varying amounts of compute while solving an individual task.

Reasoning-model benchmarks also became controversial because repeated testing can contaminate evaluation and because impressive scores do not automatically translate into reliability on open-ended real work. o3 reinforced a new direction in AI development where inference strategy and tool use mattered almost as much as base-model scale.